1. Field of the Invention
The present invention relates to a wound stator of an electric rotating machine, the process of winding the stator, and a device for using this winding process. The present invention relates more particularly to making of stators with "wavy" type windings for electric rotating machines having relatively slight power, such as alternators equipping motor vehicles.
2. The Prior Art
The stator of an alternator, such as is used in the equipment of motor vehicles, usually consists of a stack of thin sheets forming a crown where the inside face is provided with slots receiving the phase windings, generally three. In alternator stators of this type, the types of windings most often used are, on the one hand, windings consisting of coils closed on themselves and intercrossed which surround the poles, and, on the other hand, of the "wavy" type windings which are known, for example, from French patent Nos. 1,532,522, 2,408,937 and 2,483, 702.
A "wavy" type winding, to which the present invention particularly relates, comprises phase windings formed by conductors which successively go into a first slot of the stator, join a second slot on the outside, go into this second slot, reach on the outside of the third slot which is distinct from the preceding ones and located beyond, and so forth, to form a coil having a zigzag path or in an indented line. FIG. 1 of the accompanying schematic drawing reveals, in developed representation, this known principle in the case of a stator of three-phase alternator, the three phases being indicated as 1, 2, and 3, while there is mentioned as element 4 the stack of sheets with slots 5.
Windings of the type mentioned above are made either "on site,", i.e. the stator itself, by special machines, or previously formed outside the stator, then put in place in slots of the stator as provided in French patent No. 2,483,702 cited above.
In this case, the coils constituting the phases of the stator are made up of unarranged wires and, further, the ends of these coils, i.e. their part located outside the slots, overlap as can be seen in FIG. 2. Such a configuration does not permit an optimal direct cooling of the alternator; therefore, the coils must be partly cooled by heat conduction between the wires of these coils and the stack of stator sheets.
The absence of correct arrangements of the wires is also shown, on the inside stator slots, by an insufficient filling of these slots. Thus, to house the wires the slots must have a considerable depth, which increases the thickness of the stator and can result:
either in an increase of the outside diameter of the electric rotating machine,
or in a reduction of the diameter of the rotor, itself causing a limitation of power of the electric rotating machine.
The invention aims at eliminating these drawbacks, therefore at obtaining an improvement of the cooling of the stator coils, as well as a reduction of the size or an increase of power of the electric rotating machine.